Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H,W = map(int,input().split())
S = [input() for i in range(H)]
T = [[False]*W for i in range(H)]
Q = [(1,0,0)]
cnt = 0
while Q:
    q = Q.pop(0)
    if min(q)<0 or q[1]>=H or q[2]>=W:continue
    if S[q[1]][q[2]]=="#" or T[q[1]][q[2]]:continue
    if q[1]==H-1 and q[2]==W-1:
        cnt = q[0]
        break
    T[q[1]][q[2]]=True
    Q.append((q[0]+1,q[1]+1,q[2]))
    Q.append((q[0]+1,q[1]-1,q[2]))
    Q.append((q[0]+1,q[1],q[2]+1))
    Q.append((q[0]+1,q[1],q[2]-1))
ans = 0
for s in S:ans+=s.count(".")
print(ans-cnt if cnt else -1)